Photonic neuromorphic processing with coupled spiking silicon microrings

TL;DR

This paper demonstrates that coupled silicon microring resonators can serve as compact, nonlinear photonic nodes capable of complex neuromorphic computing tasks, including high-accuracy classification, with potential for on-chip training and low-power operation.

Contribution

It introduces a novel photonic core based on coupled microrings that exhibits multiple nonlinear responses and achieves high-performance neuromorphic computing in reservoir architectures.

Findings

Achieves error-free Iris classification and >97% accuracy on Sonar task.

Supports analogue, spiking, and bistable responses for versatile computing.

Operates efficiently at low powers below 4 mW.

Abstract

Understanding the physical computing mechanisms of individual network nodes is essential for scaling neuromorphic photonic architectures. This work proposes a compact passive nonlinear photonic core based on a Side-Coupled Integrated Spaced Sequence of Resonators (SCISSOR) made of three nominally equal microrings and investigate its computing capabilities. Its nonlinearities and internal feedback enable analogue, spiking, and bistable responses that are accessed by tuning the injection power and wavelength. Implemented as a single nonlinear node in a time-multiplexed reservoir computing, the SCISSOR achieves error-free classification on the Iris dataset and accuracies above 97% on the Sonar task, using both analogue and digital reservoir representations with 150 virtual nodes. In the digital scheme, spiking dynamics naturally generate sparse reservoir states, enabling efficient classification even with a single spike. Intriguingly, optimal operating points are at the boundaries where sharp transitions in dynamical complexity and/or output power occur. In these points, the SCISSOR supports high task-performance, opening novel strategies for future on-chip training. Spiking and thermal bistabilities also participate to enhance the computational performance at low injected powers below 4 mW. These results suggest optical coupled microring resonators as effective building blocks for future edge computing and neuromorphic photonic systems.